Relatives of the dead mourned the victims of the attack on the Pakistani Christian charity in Karachi on Wednesday. Click "Play" to learn more about the attack.

KARACHI, Pakistan, Sept. 25 â€” Gunmen entered the offices of a Christian welfare organization in the southern port city of Karachi on Wednesday, tying office workers to their chairs and shooting each of them in the head at close range, police and intelligence officials said. At least seven people were killed and another was critically injured.

THE SHOOTING WAS the latest in a string of violent attacks against Christians and Westerners, who have been increasingly targeted since Pakistani President Gen. Pervez Musharrafâ€™s decision to crack down on Islamic extremist groups and join the U.S. war against the Taliban and al-Qaida in neighboring Afghanistan.

The killings occurred at the third-floor offices of the Institute for Peace and Justice, or Idara-e-Amn-o-Insaf, a Pakistani Christian charity that does work in the city. Victims were tied up in chairs with their hands behind their backs and...